A former Alabama prison supervisor was behind bars after a jury convicted him Tuesday of fatally beating an inmate and conspiring to cover it up.

The federal court jury of eight women and four men returned guilty verdicts against former corrections Lt. Michael Smith. The verdicts followed six days of testimony about the fatal beating of inmate Rocrast Mack at a state prison in southeast Alabama.

Mack's family wept while listening to the jury's verdict. "Justice has been served for my son," Mack's father, Larry Mack, said outside the courtroom.

Smith, 38, of Auburn was convicted of violating Mack's constitutional rights by fatally beating him, conspiracy and obstruction of justice. He faces up to life in prison. U.S. District Judge Myron Thomson ordered him taken into custody immediately and did not set a sentencing date. Mack was led out of the courtroom with his hands cuffed behind his back.

Two other former officers at the Ventress Correctional Facility in Clayton -- Scottie Glenn and Matthew Davidson -- have pleaded guilty and are awaiting sentencing. Another former officer, Joseph Sanders, is scheduled for trial July 8.

The state Department of Corrections has had cases before where officers were fired or disciplined for abusing inmates, but the charges in Mack's death were unprecedented.

The department sought an investigation after an autopsy on Mack raised questions about Ventress employees' statements that Mack jumped on a female officer and got injured when he continued to resist officers trying to subdue him.

He said the verdict makes clear to correctional officers everywhere "that there are limits to their power and authority" and that they should listen closely to their training about when they can use force.

Mack, 24, was serving a 20-year sentence for a drug conviction from Montgomery County when he was beaten at the medium-security prison on Aug. 4, 2010. Testimony showed a female officer hit Mack first when she caught him inappropriately touching himself in his bunk. Mack hit her back, and the officer radioed for help, saying an inmate jumped on her.

Smith, the shift supervisor, and other officers responded and during the next hour, the 5-foot-11, 160-pound Mack was hit repeatedly by officers. Witnesses said Smith was angry over the female officer suffering a bloody lip, and he hit, kicked and stomped on Mack's head to send a message to other inmates that they had better not touch one of his officers. Mack died the next morning at a Montgomery hospital with bruises covering his body, his front teeth knocked out, and his brain swollen from the injuries.

The defense argued that Smith didn't know his officer had struck Mack first and he was trying to maintain order in a prison overcrowded with 1,633 inmates and only 18 guards on duty. The defense said so many officers hit Mack that it was impossible to know who struck the fatal blow.

Kewonda King, the mother of Mack's 5-year-old son, joined Mack's family outside the courthouse to reflect on the verdict.

"It lifts a weight off my heart," she said. But she said her son, Rocrast Mack Jr., still doesn't understand after nearly three years that his father is dead.

"He used to visit his daddy in jail, and he still asks me to take him to jail to see his daddy," she said.

Mack's family sued the state after his death and reached a $900,000 settlement, with $440,000 of it going to his son.